3D video systems garner great interest for enhancing a consumer's experience, whether at the cinema or in the home. These systems use stereoscopic or auto-stereoscopic methods of presentation, including:
(i) anaglyph—provides left/right eye separation by filtering the light through a two color filter, commonly red for one eye, and cyan for the other eye;
(ii) linear polarization—provides separation at the projector by filtering the left eye through a linear polarizer (commonly) oriented vertically, and filtering the right eye image through a linear polarizer oriented horizontally;
(iii) circular polarization—provides separation at the projector by filtering the left eye image through a (commonly) left handed circular polarizer, and filtering the right eye image through a right handed circular polarizer;
(iv) shutter glasses—provides separation by multiplexing the left and right images in time, and
(v) spectral separation—provides separation at the projector by filtering the left and right eye spectrally where the left and right eye each receives a complementary portion of the red, green, and blue spectrums.
Most of the 3D displays available in the market today are stereoscopic TVs, requiring the user to wear special 3D glasses in order to experience the 3D effect. Delivery of 3D content to these displays only requires carrying two separate views: a left view and a right view. Auto-stereoscopic (glasses-free) displays are in the horizon. These displays provide some amount of motion parallax; the viewer can move his/her head around as if they are viewing objects from different angles as they move around.
Traditional stereoscopic displays provide a single 3D view; however, auto-stereoscopic displays are required to provide multiple views such as five views, nine views, 28 views, etc., based on the design of the display. When regular stereoscopic content is provided to auto-stereoscopic displays, the displays extract depth maps and create or render multiple views based on this depth map. As used herein, the term “depth map” denotes an image or other bit-stream that contains information related to the distance of the surfaces of scene objects from a viewpoint. A depth map can be readily converted to a disparity map, and in the context of this document the terms depth map and disparity map are the same and inter-changeable.
The depth map also may be used for retargeting the 3D experience for different displays types with different resolutions (e.g., 1080p displays or 2K displays). There have been a number of studies showing the amount of depth designed for 3D Cinema is not suitable for smaller mobile devices and vice-versa. Also there is viewer preference to the amount of 3D depth, which can be age-dependent (the young prefer a larger depth experience than the old), culture-dependent (Asian cultures prefer higher depth than Western cultures), or simply viewer dependent. The depth map information could be used to re-render the stereo views to increase or decrease the perceived depth and other adjustments. As appreciated by the inventors here, improved techniques for delivering depth map information along with the content are desirable for improving the user experience with auto-stereoscopic and stereoscopic displays. It is further appreciated that these improved techniques preferably are backwards compatible with existing single-view and 3D systems.
The approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section. Similarly, issues identified with respect to one or more approaches should not assume to have been recognized in any prior art on the basis of this section, unless otherwise indicated.